Modulation control of hydronic systems

ABSTRACT

A hydronic heating system comprises a water line, one or more boilers, and a control. In operation, the water line facilitates a circulation of water through a building and the boiler(s) heat the water as the water flows through the water line. The control calculates a system energy load for operating boilers. The calculation of the system energy load is a function of a set-point water temperature for the hydronic heating system, a supply water temperature of water flowing relative to a supply point of the water line, a return water temperature of water flowing relative to return point of the water line and a flow rate of water flowing relative to a flow sense point of the water line.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation-in-part of U.S. applicationSer. No. 11/949,314 entitled “Modulation Control of a Hydronic HeatingSystem”, filed Dec. 3, 2007, which is a continuation-in-part of U.S.application Ser. No. 11/627,739, entitled “Hydronic Heating System”,filed Jan. 26, 2007 (collectively the “Priority Applications”). Thispresent application claims priority and benefit of the PriorityApplications to the extent the subject matter of this presentapplication is found in the Priority Applications. The content of thePriority Applications is incorporated herein by reference.

TECHNICAL FIELD

The present disclosure generally relates to modulation or control ofvarious hydronic systems utilizing one or more energy sources forparticular purposes, such as, for example, systems utilizing naturalgas, oil, coal, gasoline, steam, water, and/or electricity for purposesof providing heating, cooling, pumping, current output, and/ormechanical energy. The present disclosure specifically relates to anenergy-based modulation control of such hydronic systems.

BACKGROUND

Temperature-based modulation control schemes of boilers as known in theart are generally premised on operating the boilers as temperaturedevices based on an error calculation between a set-point temperatureand a supply temperature. More particularly, in response to the supplytemperature being less than the set-point temperature, thetemperature-based modulation control scheme would ramp up the heatingoutput of one or more of the boilers until the supply temperatureequaled the set-point temperature. Conversely, in response to the supplytemperature being greater than the set-point temperature, thetemperature-based modulation control scheme would ramp down the heatingoutput of one or more of the boilers until the supply temperatureequaled the set-point temperature.

SUMMARY

While in practice the temperature-based modulation control schemes mayhave involved various subcontrol features (e.g., aproportional-integral-derivative control feature of the rampingup/ramping down of boiler(s) or a timing control feature forenabling/disabling boiler(s), it has now been discovered that theoperation of the boilers as temperature devices impedes efficientoperation of the boilers for various reasons, primarily the absence of acalculation of a real-time heating load also known herein as an energyload or system energy load.

The present disclosure is directed to an energy load based modulationscheme of boilers generally premised on operating the boilers as energydevices based on a calculation of a real-time heating load/energy load.

One form of the present disclosure is a hydronic heating system with awater line, one or more boilers and a control. In operation, the waterline facilitates a circulation of water through a building and theboiler(s) heats the water as the water flows through the water line. Thecontrol calculates a system energy load for operating boilers. Thecalculation of the system energy load is a function of a set-point watertemperature for the hydronic heating system, a supply water temperatureof water flowing relative to a supply point of the water line, a returnwater temperature of water flowing relative to return point of the waterline, and a flow rate of water flowing relative to a flow sense point ofthe water line.

The foregoing form and other forms of the present disclosure as well asvarious features and advantages of the present disclosure will becomefurther apparent from the following detailed description of variousembodiments of the present disclosure read in conjunction with theaccompanying drawings. The detailed description and drawings are merelyillustrative of the present disclosure rather than limiting, the scopeof the present disclosure being defined by the appended claims andequivalents thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic and block diagram of an embodiment of the presentdisclosure, illustrating a hybrid heating system having two boilers.

FIG. 2 is a schematic and block diagram of an embodiment of the presentdisclosure, illustrating a hybrid heating system having four boilers.

FIG. 3 is a schematic and block diagram of the main control circuit usedin a heating system constructed in accordance with an embodiment of thepresent disclosure.

FIG. 4 is a schematic and block diagram of condensing boiler controlcircuitry used in a heating system constructed in accordance with anembodiment of the present disclosure.

FIG. 5 is a schematic and block diagram of non-condensing boiler controlcircuitry used in a heating system constructed in accordance with anembodiment of the present disclosure.

FIG. 6 is a schematic and block diagram of a pH measurement controlcircuit used in a heating system constructed in accordance with anembodiment of the present disclosure.

FIG. 7 is a schematic and block diagram illustrating a number oftemperature sensor circuits, as well as a user interface circuit used ina heating system constructed in accordance with an embodiment of thepresent disclosure.

FIG. 8 is a flowchart representative of a process modulation algorithmin accordance with an embodiment of the present disclosure.

FIG. 9 is a flowchart representative of a rate-of-change modulationscheme in accordance with an embodiment of the present disclosure.

FIG. 10 is a schematic and block diagram of a single system controllerfor a plurality of devices constructed in accordance with an embodimentof the present disclosure.

FIG. 11 is a schematic and block diagram of a system administrator andcorresponding device controllers for a plurality of devices constructedin accordance with an embodiment of the present disclosure.

FIG. 12 is a schematic and block diagram of an exemplary embodiment ahybrid heating system of the present disclosure illustrating acondensing plant and a non-condensing plant.

FIG. 13 is a flowchart representative of an exemplary embodiment ofhybrid energy load calculation method of the present disclosure.

FIGS. 14A and 14B are schematic and block diagrams of an exemplaryembodiment an energy exchange system of the present disclosureillustrating a boiler pipe system and a chiller pipe system.

FIGS. 15A and 15B are state diagrams of an exemplary operation of theenergy exchange system illustrated in FIGS. 14A and 14B.

FIG. 16 is a schematic and block diagram of an exemplary embodiment of agas efficiency boiler of the present disclosure.

FIG. 17 is a schematic and block diagram of an exemplary embodiment of agas efficiency system of the present disclosure.

FIG. 18 is a schematic and block diagram of an exemplary embodiment of apumping system of the present disclosure.

FIG. 19 is a flowchart representative of an exemplary embodiment of a ΔTpumping method of the present disclosure.

DETAILED DESCRIPTION

For the purposes of promoting an understanding of the principles of thedisclosure, reference will now be made to the embodiments illustrated inthe drawings, and specific language will be used to describe the same.It will nevertheless be understood that no limitation of the scope ofthe disclosure is thereby intended, and alterations and modifications inthe illustrated examples, and further applications of the principles ofthe disclosure as illustrated therein are herein contemplated as wouldnormally occur to one skilled in the art to which the disclosurerelates.

Referring to FIG. 1, there is shown a hydronic (i.e., hot water) heatingsystem 20 that includes boilers 21 and 22 for heating water that iscirculated in order to heat a building. Boilers 21 and 22 may both becondensing or non-condensing boilers, or one boiler may be a condensingboiler while the other is a non-condensing boiler. Boilers 21 and 22 arerespectively associated with pumps 23 and 24 that act to providecirculation of the heated water throughout the building. Controller 36is operably connected to boilers 21 and 22 via connectors 42 and 43respectively. Connectors 42 and 43 are illustratively shown as being acable or wire, but connectors 42 and 43, as well as other connectorsdescribed and shown herein, may take the form of an apparatus orfunctionality consistent with any technology known to those skilled inthe art and appropriate for the purpose and application described (e.g.,wireless transmission technology). Controller 36 provides signals thatcontrol the operation of boilers 21 and 22, including the operation oftheir respective boiler pumps 23 and 24. A temperature sensor 25 islocated to measure the water temperature in boiler inlet or return waterline 27 of boiler 21. Temperature sensor 25 is operably connected tocontroller 36 via connector 32. Temperature sensor 26 is located tomeasure the water temperature in outlet or system supply water line 28of boiler 21 and is operably connected to controller 36 via connector33. Similarly, a temperature sensor 29 is located to measure the watertemperature in inlet or return water line 31 of boiler 22. Temperaturesensor 29 is operably connected to controller 36 via connector 34.Temperature sensor 30 is located to measure the water temperature inoutlet or system supply water line 32 of boiler 22 and is operablyconnected to controller 36 via connector 35.

Water lines 27, 28, 31, and 32 are connected to the main circulatingwater line 37 that circulates heated water through heat transmissiondevices 18 and 19 (e.g., heat exchangers, radiators, or air handlers)located at various points throughout the building to heat the building.Auxiliary pumps 38 and 39 are connected to main water line 37 to assistthe water flow. Pumps 38 and 39 are connected via connectors 40 and 41,respectively, to controller 36 to provide control of pumps 38 and 39.Water flow direction in heating system 20 is indicated by arrows 95 inFIG. 1.

Additional temperature sensors 44, 45, and 46 are located along mainwater line 37 to measure the temperature of the water at that location,and return the temperature data via data lines 47, 48, and 49,respectively, to controller 36, although it is understood thattemperature data may be returned in a non-wired manner, e.g., wirelesstransmission, as would be known to those skilled in the art. Sensor 44is illustratively shown as being located in the vicinity of the outgoingheated water from boilers 21 and 22, respectively. Sensor 45 isillustratively shown as being located in between boilers 21 and 22 tomeasure water temperature in the return portion of main water line 37.Sensor 46 is illustratively shown as being located in the return waterflow from heat transmission devices 18 and 19 to boilers 21 and 22. Anoutside air temperature sensor 50 is connected to controller 36 via dataline 51 to provide measurements of outside air temperature to controller36 of heating system 20.

Air temperature sensors 80 and 81 are illustratively shown as beingconnected to controller 36 via connectors 82 and 83, respectively. Airtemperature sensors 80 and 81 are illustratively located in rooms orareas of the building to be heated, and provide data to controller 36regarding the ambient temperature of those rooms or areas.

Dampers 52 and 53 are illustratively shown as being controlled viaconnectors 54 and 55, respectively, by controller 36 for controllingoutside air flow to boilers 21 and 22, respectively, in order to providefree air make-up to boilers 21 and 22. Flow valves 56, 57, 58, and 62are illustratively shown as being connected to and controlled bycontroller 36 via connectors 59, 60, 61, and 63, respectively. The rateand quantity of soft or conditioned water supplied to flush by-pass orsidestream water line 64 via incoming water line 70, in order tomaintain calibration of pH meter 67 located in sidestream water line 64,is controlled by way of flow valves 57 and 58. Water is drained frommain water line 37 via drain line 17 by way of flow valves 56 and 58. pHmeter 67 measures the pH of the water within main water line 37. Mainvalve 75 is located within main water line 37 and is illustrativelyshown as being connected to controller 36 by connector 76 to force waterflow through sidestream water line 64. Connector 71 connects pH meter 67to controller 36. Flow measuring device 65 is mounted to main water line37 and provides flow data via connector 66 to controller 36. A userinterface 90, e.g., computer input screen, is illustratively shown asbeing connected to controller 36 by way of connector 91.

It will be understood that the system of FIG. 1 is illustrative innature and is not limited to any specific number of boilers, anyparticular piping arrangement of the various water lines, valves,sensors or controls shown in the drawings, which will in operationdepend upon particular building requirements.

To further illustrate the non-limiting nature of the present disclosure,reference is now made to FIG. 2, which illustrates a heating system 120.Heating system 120 illustratively includes non-condensing boilers 121and 122 and condensing boilers 123 and 124 connected to a main watercirculation line 147 by inlet or boiler return water lines 126, 127,128, and 129, respectively and outlet or system supply water lines 130,131, 132, and 133, respectively. Boilers 121, 122, 123, and 124 arerespectively associated with pumps 134, 135, 136, and 137 which aremounted on the boiler return water lines 126, 127, 128, and 129,respectively. Pumps 134, 135, 136, and 137 are preferably enabled withvariable frequency drive circuitry that allows the pumps to be operatedat variable speeds, i.e., pumping rates. Similar to heating system 20 ofFIG. 1, heating system 120 of FIG. 2 includes temperature sensors 138,140, 142, and 144 mounted on the outlet or system supply water lines130, 131, 132, and 133, respectively, and temperature sensors 139, 141,143, and 145 mounted on the inlet or return water lines 126, 127, 128,and 129, respectively. Boilers 121, 122, 123, and 124 are operablyconnected to controller 146 via connectors 221, 222, 223, and 224,respectively. Pumps 134, 135, 136, and 137 are operably connected tocontroller 146 via connectors 234, 235, 236, and 237, respectively.Temperature sensors 138, 139, 140, 141, 142, 143, 144, and 145 areoperably connected to a controller 146 via connectors 238, 239, 240,241, 242, 243, 244, and 245, respectively. While FIG. 2 shows controller146 connected to the various components herein described via hard wiredcontrol or connection lines or wires, it will be understood that variouswireless connections are envisioned including, but not limited to, IR,RF, and optical links. In addition, control and sensor data may becommunicated via various network interfaces and protocols includingparallel or serial data buses, Ethernet, Bluetooth, IEEE standardcontrol interfaces, or other computer or data networks that are known tothose of ordinary skill in the art both now and as may be developed inthe future.

Boilers 121, 122, 123, and 124 include air dampers 148, 149, 150, and151, which are also operably connected to controller 146 via connectors248, 249, 250, and 251, respectively. Controller 146 may independentlycontrol the operation of air dampers 148, 149, 150, and 151 viaswitching or control signals, e.g., digital signals, sent to dampers148, 149, 150, and 151 via connectors 248, 249, 250, and 251 to controlthe outside or free air make-up to boilers 121, 122, 123, and 124,respectively. Auxiliary pumps 152 and 153 pump or circulate waterthrough secondary water line 154 of main water line 147 and are operatedby controller 146 via connectors 252 and 253, respectively. Auxiliarypumps 155 and 156 pump or circulate water through secondary water line157 and are operated by controller 146 via connectors 255 and 256,respectively. Water flow direction through system 120 is illustrativelyshown by arrows 200.

Valves 167 and 170 are connected to and controlled by controller 146 viaconnectors 267 and 270, respectively, to provide soft or conditionedwater via inlet line 168 to flush sidestream 185 as necessary tomaintain the calibration of pH meter 172. Controller 146 is alsooperably connected to sidestream valves 166 and 169 via connectors 266and 269, respectively, to control the flow of water from main water line147 to a pH measurement sidestream water line 185. A pH meter 172 isprovided to measure the pH of the water circulating throughout system120. pH meter 172 is shown as being mounted in pH measurement sidestream185 and operably connected to controller 146 via connector 272. Mainvalve 165 is mounted within main water line 147 and is also operablyconnected to controller 146 via connector 265. Controller 146 operatesmain valve 165 to force the flow of water through pH measurementsidestream 185. A weak acid pump 195 and a weak base pump 196 areillustratively shown as being coupled into main water line 147. Acidpump 195 and base pump 196 are shown as being operably connected tocontroller 146 via connectors 295 and 296, respectively. Controlling thepH of the water circulating through main water line 147 is important toprevent premature failure or wear with respect to the components ofheating system 120 due to overly acidic or basic water. Through theoperation of valves 165, 166, 167, 169, and 170 by controller 146 bysignals via connectors 265, 266, 267, 269, and 270, respectively,periodic checks of the pH of the water in main water line 147 can bemade by diverting some water into sidestream 185 and measuring its pH bypH measurement sensor 172 and returning that data to controller 146 viaconnector 272. If the water requires an adjustment of its pH, controller146 can initiate the operation of weak acid pump 195 or weak base pump196 by signals sent via connectors 295 or 296, respectively, as neededto restore the pH of the water in main water line 147 to a satisfactorylevel.

Temperature sensors 160, 161, and 162 are mounted to main water line 147to measure the temperature of the circulating water at various locationsalong main water line 147. Sensors 160, 161, and 162 are shown as beingoperably connected to controller 146 via connectors 260, 261, and 262,respectively. A flow measuring device 163 is shown as being mounted onmain water line 147 to provide water flow information to controller 146via connector 263. An outdoor air temperature sensor 164 is mountedoutside the building and is operably connected to controller 146 viaconnector 264. Air temperature sensors 180 and 181 are located in roomsor areas of the building and are also operably connected to controller146 via connectors 280 and 281, respectively, to provide informationwith respect to the ambient temperature of the rooms or areas in whichthe sensors are located. FIG. 2 illustratively shows heat transmissiondevices 201 and 202 located within system 120. Devices 120 may beend-user heat distribution apparatus, such as radiators, heatexchangers, or air handlers, for only a few examples. A user interfacedevice 190 is also operably connected to controller 146 via connector290 to allow a user of heating system 120 to select or change variousinput criteria, e.g., desired room temperature or the manner in whichheating system 120 is operated. User interface device 190 also providesa means for information regarding the status or condition of thecomponents of system 120 to be communicated to the user.

The piping configuration of main water line 37 shown in FIG. 1 and mainwater line 147 shown in FIG. 2 locates the condensing boilers 123 and124 upstream from the non-condensing boilers 121 and 122 such thatduring the time the condensing boilers are enabled, their operation willpre-heat the water flowing to the non-condensing boilers, therebyincreasing the efficiency of the non-condensing boilers and acting toprevent the non-condensing boilers from condensing, thereby protectingthe non-condensing boilers from the detrimental effects of condensation.

As previously described, the present disclosure does not limit thenumber or types of boilers that can be used within a heating system. Forpurposes of explaining the operation of a heating system constructed inaccordance with the present disclosure, reference will be made to FIGS.3-7 which, for example only, illustrate elements of a hydronic heatingsystem that includes two condensing and two non-condensing boilers in anarrangement such as that shown in FIG. 2. Reference will therefore bemade primarily to FIG. 2, although it is understood that the principlesof operation to be described apply equally to heating systems havingdifferent numbers and types of boilers, including but not limited to thesystem of FIG. 1.

FIG. 3 illustrates the presence of a main system controller and itsassociated input and output signals and functions. FIG. 4 illustratesthe presence of a condensing boiler controller and its associated inputand output signals and functions. FIG. 5 illustrates a non-condensingboiler controller with its associated input and output signals andfunctions, and FIG. 6 illustrates a pH measurement controller and itsassociated input and output signals and functions. It is understood thatwhile separate or individual controllers can of course be used, aunitary controller, such as controller 36 or 146, may comprise thefunctionality of each of the controller elements shown in FIGS. 3-6 inthe physical embodiment of a single device. Therefore, for purposes ofsimplifying the following explanation, each of the controller devices inFIGS. 3-6 will be identified by reference number 146. Additionally,while FIGS. 3-7 may illustrate elements that contain language thatsuggests a function or type of information, that element may beidentified by a reference number that corresponds to the physical deviceshown in FIG. 2 that performs such function or provides suchinformation. FIG. 7 illustrates a representation of the functionalitywithin heating system 120 of user interface 190 as well as a number ofrepresentative temperature sensors, e.g., sensors 160, 164, 180, and181.

Through the use of user interface device 190, the type of each boiler121-124 (e.g., condensing or non-condensing) will be inputted by theuser. Minimum and maximum return and supply temperatures for each ofboilers 121-124, as defined by the boiler manufacturer, will be inputtedby the user as well. The outdoor air temperature switch point, i.e., thetemperature above which a condensing-type boiler is initially selected,may also be provided to system 120 via user interface device 190. Usingdata provided by interface device 190 and the outdoor air temperatureprovided by sensor 164 via connector 264, controller 146 will enable atleast one of pumps 134-137 via their respective connectors 234-237.After a user-defined delay (e.g., 1 to 10 minutes), a flow reading usingflow sensor 163 in the main water line 147 will be taken. Using thisflow data provided via connector 263, as well as other initializingdata, controller 146 calculates an initial building heating load forsystem 120. Based on this calculated load and the outdoor airtemperature switch point, controller 146 will determine which type ofboiler (e.g., condensing or non-condensing) to initially enable. Forexample, if the outdoor air temperature calls for a condensing boiler,and there is more than one condensing boiler available in system 120,then the first boiler selected can be based on which one has accumulatedthe fewest hours of operation. This may be done by comparing timerslinked with each boiler's respective output enable circuits, unless aparticular boiler in the system has been designated a dedicated leadboiler, in which case it will always be enabled or fired first. Sincecontroller 146 also knows the output capability of each boiler on thesystem, controller 146 may also select for operation the boiler havingan output that is most closely matched to the building heating load. Ifthe condition should exist that a particular boiler is in an alarm state(i.e., the boiler is not working properly), controller 146 will notenable that boiler until the condition causing the alarm is remedied.For purposes of this example, condensing boiler 124 is initially enabledby controller 146 via connector 224. After an initial period of low-fireoutput of boiler 124, the building heating load will be recalculated toobtain a real-time heating load. This low-fire time delay, e.g., 30minutes, is used to ensure that the initial calculated building heatingload is accurate so as to avoid overshooting the desired buildingtemperature by overfiring the initially enabled or fired boiler orboilers. If the recalculated real-time heating load indicates that heatis still required, the initially enabled boiler 124 will thereafter byoperated in its normal or real-time mode, e.g., viaproportional-integral-derivative (PID) control, by controller 146 viaconnector 224.

The operation of the PID mode of controller 146 will be constantlymonitored. If controller 146 causes the output of boiler 124 to remainabove a user-defined output percentage (e.g., 25%-100%) for a givenuser-defined time period (e.g., 5-60 minutes), then a second boiler,e.g., condensing boiler 123, will be enabled via connector 223, andcontroller 146 will split the real-time heating load between the twoenabled boilers 124 and 123 in a manner that operates both boilers asefficiently as possible. The real-time heating load distribution betweenboilers 124 and 123 is monitored often (e.g., once per second) to ensureboilers 124 and 123 continue to be operated as efficiently as possible.In this exemplary embodiment, if the real-time heating load increases,this pattern of sequencing will continue until all boilers of aparticular type (e.g., condensing or non-condensing) that exist in agiven heating system have been enabled or fired. Should the outdoor airtemperature remain above the condensing/non-condensing switch point andall condensing boilers, in this case boilers 124 and 123, have beenoperating at a user-defined maximum output for a user-defined period oftime, and a user-defined heating load percentage (e.g., 1-10%) has notbeen reached, a non-condensing boiler, e.g., boiler 122 will then beenabled by an enabling signal via connector 222. Once non-condensingboiler 122 has been enabled, condensing boilers 124 and 123, that arestill enabled, will be reset to cover that portion of the real-timeheating load that still allows non-condensing boiler 122 to maintain itsminimum recommended return water temperature. Non-condensing boiler 122will operate under PID control to cover the balance of the real-timeheating load. Should the real-time heating load increase, thenon-condensing boilers will follow the same sequencing control describedabove to enable and control additional non-condensing boilers, e.g.,boiler 121, and boiler pumps, e.g., pump 134. During the run cycles ofboth condensing and non-condensing boiler reset loops, building zonetemperatures will be polled by networked temperature devices, e.g.,sensors 180 and 181, to determine if the output (i.e., supplytemperature) of system 120 is meeting the real-time heating load. Basedon this information, boiler reset temperatures will be increased tosupply more heat if needed, decreased to increase efficiency of boileroperation, or left the same. This polling enables controller 146 to knowhow much energy has been used to heat the building and, based on thecalculated real-time heating load, enable only the boiler or boilersneeded to most efficiently meet the remaining real-time heating load.

Once the real-time heating load covered by condensing boilers 124 and123 has been satisfied, condensing boilers 124 and 123 will be shut downby controller 146 by signals provided via connectors 224 and 223,respectively. Condensing boilers 124 and 123 will be enabled again onlyif the return water temperature of non-condensing boilers 121 and 122(if enabled) falls below a user defined limit (e.g., 130° F.) andremains there for more than a user-defined period of time (e.g., 5-30minutes), or if the outdoor air temperature rises above thecondensing/non-condensing switch point, or if all the non-condensingboilers, in this case boilers 121 and 122, are operating at auser-defined maximum output for a user-defined period of time (e.g.,15-60 minutes) and have failed to adequately satisfy the real-timeheating load. As the real-time heating load is satisfied or reduced, anon-condensing boiler will be shut down by controller 146. The boilerselected for shut down is chosen based on hours of operation. As thereal-time heating load continues to decrease, additional boilers will beshut down. Boiler operating regulations require that a boiler must beshut down at least once every 24 hours. In order to comply with thisrequirement and to even wear across boilers, system 120 operates suchthat each boiler 121-124 is shut down at least once every six hours.This process allows controller 146 to regularly compare hours ofaccumulated operation and enable or fire the boiler of a given type withthe least operating hours first. If the real-time heating load of thebuilding is determined to be less than the minimum operating range ofall the available boilers 121-124 on system 120, controller 146 willselect and enable the boiler having the lowest operating range. Thisfunctionality of controller 146 will help to eliminate as much aspossible the efficiency losses and significant wear effects of shortcycling on boilers 121-124.

When the switch to non-condensing boilers occurs because outdoor airtemperature has dropped below the switch point, all of the real-timeheating load will be assigned to non-condensing boilers 121 and 122.Once a non-condensing boiler has been enabled or fired as describedabove and the return water temperature is equal to or greater than auser defined limit (e.g., 130° F.), any condensing boilers (e.g., boiler123 or 124) that are enabled will be shut down, although their mainpumps will continue to operate for a period of time that is calculatedas a percentage of the boiler's just-concluded run time in order toextract additional heat from that boiler and reduce the effects ofboiler precipitation on scaling of the boiler tubes. The total load willthen be assigned to the running non-condensing boiler and the reset ofthe supply or output temperature will be defined by an equation having aslope which is designated for non-condensing boilers.

The inlet and outlet temperature difference, i.e., ΔT, is a user-definedvalue (e.g., 10° F.-45° F. or within the boiler manufacturer's limits)that can be selected via user interface device 190. This ΔT, measured bytemperature sensors 144 and 145 for boiler 124, for example, ismaintained to the extent possible via operation of controller 146 byproviding control signals to the variable frequency drives of theboiler's respective pump, e.g., pump 137 in the above example. Pump 137,for example, will then be modulated or operated to increase or decreasewater flow so as to maintain the measured ΔT with the user selectedvalue. By modulating or controlling the flow rate of the boiler pumps,the pumps can put out less water at higher temperatures, therebyincreasing boiler efficiency.

It can be seen from the previous explanation with reference to thedrawings that system 120 provides microprocessor control of differingtypes of boilers in a heating system through the use of a variety ofsensor inputs to optimally sequence and operate each boiler in theheating system to maximize efficiency of the boilers. The system issuitable for controlling multiple boilers of different sizes and ofdifferent types within the same heating system. By calculating real-timeheating load and using that information to select and operate boilers,efficiency losses and detrimental effects on equipment life due toshort-cycling of boilers are prevented or eliminated. The systemdisclosed herein effectively prevents non-condensing boilers fromcondensing while condensing boilers are allowed to condense. The systemoffers the ability to reset and control both condensing andnon-condensing boilers on the same system. With two unique and userdefinable reset temperature slopes, both types of boilers can beutilized seamlessly.

The controllers shown in FIGS. 3-6 were described in the context ofimplementing a PID version of a process modulation algorithm of thepresent disclosure for purposes of controlling a hybrid boiler system.In practice, the process modulation algorithm is applicable to manytypes of systems including, but not limited to, systems employingdevices using energy sources (e.g., natural gas, oil, coal, gasoline,steam, water, and electricity) for any purpose (e.g., heating, cooling,pumping, current output, and mechanical energy). To facilitate furtherunderstanding of the process modulation algorithm of the presentdisclosure in the context of any system and to introduce arate-of-change modulation version of the process modulation algorithm,descriptions will now be provided herein of a flowchart 300representative of the process modulation algorithm as shown in FIG. 8and of a flowchart 400 representative of the rate-of-change modulationversion of the process modulation algorithm as shown in FIG. 9.

Referring to FIG. 8, a stage S302 of flowchart 300 encompasses a systemenergy load calculation that is dependent upon one or more operationalconditions (e.g., temperature, pressure, power consumption, motion,etc.) of an applicable system (e.g., heating, cooling, pumping, currentoutput, and mechanical energy). For example, in the context of a hybridheating system including one or more condensing boilers and one or morenon-condensing boilers, the following equations [1] and [2] can beutilized for purposes of calculating a system energy load for the hybridheating system that is dependent upon a set-point temperature of thehybrid heating system:

L=((T _(SP) −T _(R))+(T _(SP) −T _(S)))*(GPM*WLG*MPH)   [1]

L=((T _(SP) −T _(R))+(T_(SP) −T _(S))+(CTL−T _(R)))*(GPM*WLG*MPH)   [2]

where (1) L is a calculated system energy load (BTU/H) for the hybridheating system,

(2) T_(SP) is the set-point temperature (° F.) of the hybrid heatingsystem,

(3) T_(S) is the supply water temperature (° F.) of the hybrid heatingsystem,

(4) T_(R) is the return water temperature (° F.) of the hybrid heatingsystem,

(5) GPM is the number of gallons per minute flowing through the hybridheating system past a flow sense point,

(6) WLG is the pounds of water per gallon within the hybrid heatingsystem,

(7) MPH is the minutes per hour the hybrid heating system is expected tobe operational for an hour time period, and

(8) CTL is a condensing temperature limit (° F.) of the hybrid heatingsystem.

Equation [1] is utilized for all condensing operations and fornon-condensing operations whereby the return water temperature T_(R) isequal to or greater than the condensing temperature limit CTL.Conversely, equation [2] is utilized for non-condensing operationswhereby the return water temperature T_(R) is less than the condensingtemperature limit CTL. As previously described herein, a hybrid heatingsystem can be switched between condensing operations and non-condensingoperations based on a comparison of the outdoor air temperature to aswitch temperature point whereby condensing operations primarily occurabove the switch temperature point and non-condensing operationsprimarily occur below the switch temperature point.

A determination of the set-point temperature is also dependent uponwhether the hybrid heating system is in condensing operations ornon-condensing operations. For example, a condensing reset temperatureslope is derived from a graph of a water temperature range and outputair temperature range for the condensing boiler(s). For this slope, oneendpoint is plotted as the maximum water temperature/minimum outdoor airtemperature and the other endpoint is plotted as the minimum watertemperature/maximum outdoor air temperature, whereby the set-pointtemperature is the water temperature on the slope corresponding to asensed outdoor air temperature. Similarly, a non-condensing resettemperature slope is derived from a graph of a water temperature rangeand output air temperature range for the non-condensing boiler(s).Again, for this slope, one endpoint is plotted as the maximum watertemperature/minimum outdoor air temperature and the other endpoint isplotted as the minimum water temperature/maximum outdoor air temperaturewhereby the set-point temperature is the water temperature on the slopecorresponding to a sensed outdoor air temperature.

Still referring to FIG. 8, a stage S304 of flowchart 300 encompasses adevice load assignment that is dependent upon the output capacities ofthe device(s) (e.g., boilers, chillers, pumps, dampers, etc.) of theapplicable system (e.g., heating, cooling, pumping, current output andmechanical energy). For example, in the context of a hybrid heatingsystem including one or more condensing boilers and one or morenon-condensing boilers, the following equations [3] and [4] can beutilized for purposes of assigning a device load for each boiler Y of atotal of X enabled boilers of the hybrid heating system:

BY _(IL)=(OY _(MAX) /ΣOX _(MAX)))*(L)   [3]

BY _(IL)=(OY _(MIN) /ΣOX _(MIN)))*(L)   [4]

where (1) BY_(IL) is a load assignment (BTU/H) for a particular boilerY,

(2) OY_(MAX) is the maximum output (BTU/H) for a particular boiler Y,

(3) ΣOX_(MAX) is a summation of all maximum outputs (BTU/H) for theenabled boilers X,

(4) OY_(MIN) is the minimum output (BTU/H) for a particular boiler Y,

(5) ΣOX_(MIN) is a summation of all minimum outputs (BTU/H) for theenabled boilers X, and

(6) L is the previously calculated system energy load (BTU/H) for thehybrid heating system.

Equation [3] is utilized whenever all of the control signal(s) (e.g.,analog or digital, voltage or current) of the enabled boiler(s) X are tobe modulated as described herein. Conversely, equation [4] is utilizedwhenever less than all of the control signal(s) (e.g., analog ordigital, voltage or current) of the enabled boiler(s) X are to bemodulated as described herein. As previously described herein, thedetermination of which boiler(s) to enable at any given moment is afunction of the operational state of the system (i.e., condensing ornon-condensing) as well as the operational state of each boiler in termsof at least an online/offline status of the boiler, and an operationaltime status of the boiler.

Stages S302 and S304 are initially executed prior to the conclusion ofthe low fire time delay of the hybrid heating system and thereafter arecontinually executed on a periodic basis to maintain a dynamic efficientcontrol of the hybrid heating system.

Still referring to FIG. 8, a stage S306 of flowchart 300 encompasses adevice output error calculation that is based on a comparison of anassigned device load and a device output for each enabled device (e.g.,boiler, chiller, pump, damper, etc.) of the applicable system (e.g.,heating, cooling, pumping, current output and mechanical energy). Forexample, in the context of a hybrid heating system including one or morecondensing boilers and one or more non-condensing boilers, the followingequations [5]-[10] can be utilized for purposes of calculating a deviceoutput error for each enabled boiler of the hybrid heating system:

BY_(SP)≈BY_(IL)   [5]

BY _(HL) =OY _(MAX) +DB   [6]

BY _(LL) =OY _(MIN) −DB   [7]

DB=OF*(OY _(MAX)/100)   [8]

O _(BY)=(V _(CON) −V _(MIN))*((OY _(MAX) −OY _(MIN))/(V _(MAX) −V_(MIN)))+OY _(MIN)   [9]

E _(Y) =BY _(SP) −O _(BY)   [10]

where (1) BY_(SP) is the boiler output set-point temperature (BTU/H) fora particular boiler Y,

(2) BY_(IL) is the previously calculated load assignment (BTU/H) for aparticular boiler Y,

(3) BY_(HL) is a high limit for the boiler output set-point temperatureBY_(SP),

(4) BY_(LL) is a low limit for the boiler output set-point temperatureBY_(SP),

(5) OY_(MAX) is the maximum output (BTU/H) for a particular boiler Y,

(6) OY_(MIN) is the minimum output (BTU/H) for a particular boiler Y,

(7) DB is a deadband based on an output percentage factor OPF of aparticular boiler Y, whereby the output percentage factor OPF can bedesigned to range from 1 to 100,

(8) O_(BY) is a calculated heat output (BTU/H) for a particular boilerY,

(9) V_(CON) is an analog control voltage signal for a particular boilerY that controls the fire level of that boiler Y,

(10) V_(MAX) is a maximum of the analog control voltage signal V_(CON)(e.g., 10 volts),

(11) V_(MIN) is a minimum of the analog control voltage signal V_(CON)(e.g., 0 volts), and

(12) E_(Y) is the calculated error for a particular boiler Y.

While equations [5]-[10] can be executed during the low fire time delayof the hybrid heating system, it is only of particular interest forequations [5]-[8] to be executed or processed during the low fire timedelay and all of the equations [5]-[10] to be executed continually on aperiodic basis upon completion of the low fire time delay.

Also note that the boiler output set-point temperature BY_(SP) is afunction of the calculated load assignment BY_(IL) that can dynamicallyvary between the low limit BY_(LL) and the high limit BY_(HL). As such,those having ordinary skill in the art will appreciate the purpose ofutilizing the deadband DB to establish the low limit BY_(LL) and thehigh limit BY_(HL) is to limit the dynamic variable nature of thecalculated load assignment BY_(IL). For a hybrid heating system, theoutput percentage factor OPF is preferably 1 for stage S306.

Furthermore, during the low fire period, it is best to ramp the analogcontrol voltage signal V_(CON) at a fixed rate in the appropriate up ordown direction based on the calculated error E_(Y) in an attempt toreach the boiler output set-point temperature BY_(SP) during the lowfire period in a controlled manner. Thereafter, the control voltagesignal V_(CON) is modulated in the appropriate positive or negativedirection based on the calculated error E_(Y) in accordance with stageS308 of flowchart 300.

Specifically, stage S308 encompasses a modulation of an output of adevice (e.g., boiler, chiller, pump, damper, etc.) based on thecalculated device output error in accordance with a modulation schemechosen for an applicable system (e.g., heating, cooling, pumping,current output and mechanical energy). For example, in the context of ahybrid heating system including one or more condensing boilers and oneor more non-condensing boilers, a modulation of an output of an enabledboiler based on a calculated device output error of that enabled boilermay be in accordance with the PID modulation scheme previously describedherein. In another exemplary embodiment, the chosen modulation scheme isa rate-of-change modulation scheme as represented by the flowchart 400shown in FIG. 9.

Referring to FIG. 9, a stage S402 of flowchart 400 encompasses acalculation of a modulation control variable. For example, in thecontext of a hybrid heating system including one or more condensingboilers and one or more non-condensing boilers, the following equations[11]-[17] can be utilized for purposes of calculating the modulationcontrol variable:

IF E _(Y)↑ and E _(Y)>+DB, THEN CV_(Y)=CV_(Y)+2   [11]

IF E _(Y)↑ and E _(Y)<−DB, THEN CV_(Y)=CV_(Y)−2   [12]

IF E _(Y)↓ and E _(Y)>+DB, THEN CV_(Y)=CV_(Y)+1   [13]

IF E _(Y)↓ and E _(Y)<−DB, THEN CV_(Y)=CV_(Y)−1   [14]

IF E _(Y)<DB and E _(Y)>−DB, THEN CV_(Y)=CV_(Y)+0   [15]

CV_(LL)=(ADCF)*V _(MIN)   [16]

CV_(HL)=(ADCF)*V _(MAX)   [17]

where (1) CV_(Y) is the modulation control variable for a particularboiler Y that varies between a low limit CV_(LL) and a high limitCV_(HL) (initially equal to low limit CV_(LL) upon the enablement of theboiler),

(2) E_(Y) is the calculated error for a particular boiler Y, and

(3) ADCF is an analog-to-digital conversion factor corresponding to anumber of bit states of a digital analog voltage signal AN_(Y) dividedby the maximum voltage V_(MAX) for the analog control voltage signalV_(CON).

Again, those having ordinary skill in the art will appreciate that thepurpose of utilizing the deadband DB to control the calculation for themodulation control variable CV_(Y) is to limit the dynamic variablenature of the calculated error E_(Y), which is a function of the dynamicvariable nature of calculated load assignment BY_(IL). For a hybridheating system, the output percentage factor OPF is preferably 1 forstage S402.

Furthermore, the following equation [18] can be utilized to prevent anoversaturation of the modulation control variable CV_(Y):

IF E_(Y)<DB, THEN CV_(Y)=AN_(Y)   [18]

where AN_(Y) is the digital conversion of the analog control voltagesignal V_(CON) that will be further explained subsequently herein.Preferably, the output percentage factor OPF for deadband DB is 50 forthe oversaturation protection of the modulation control variable CV_(Y).

A stage S404 of flowchart 400 encompasses a calculation of a controlsignal for each enable device (e.g., boiler, chiller, pump, damper,etc.) of the applicable system (e.g., heating, cooling, pumping, currentoutput, and mechanical energy) as a function of the previouslycalculated modulation control variable CV_(Y). For example, in thecontext of a hybrid heating system including one or more condensingboilers and one or more non-condensing boilers, the following equations[19]-[21] can be utilized for purposes of calculating an unbiaseddigital control voltage signal AN_(Y) of Z bits (e.g., 12 bits):

IF CV_(Y)>AN_(Y), THEN AN_(Y)=AN_(Y)+1   [19]

IF CV_(Y)<AN_(Y), THEN AN_(Y)=AN_(Y)−1   [20]

IF CV_(Y)=AN_(Y), THEN AN_(Y)=AN_(Y)−0   [21]

The following equations [22]-[27] can be utilized for purposes ofcalculating a biased ramp down of digital control voltage signal AN_(Y)of Z bits (e.g., 12 bits):

R _(PG1)=(V _(G)*10*B _(E))/(OY _(MAX)/1000)/10   [22]

R_(PG2)=2R_(PG1)   [23]

IF CV_(Y)>AN_(Y), THEN AN_(Y)=AN_(Y)+1   [24]

IF CV_(Y)<AN_(Y) AND E _(Y)<−DB, THEN AN_(Y)=AN_(Y) −R _(PG1)   [25]

IF CV_(Y)<AN_(Y) AND E _(Y)>−DB, THEN AN_(Y)=AN_(Y) −R _(PG2)   [26]

IF CV_(Y)=AN_(Y), THEN AN_(Y)=AN_(Y)−0   [27]

where (1) R_(PG1) is the base-biased ramp-down variable for a particularboiler Y,

(2) V_(G) is the water volume of a particular boiler Y in gallons,

(3) B_(E) is a maximum rated efficiency of a particular boiler Y,

(4) OY_(MAX) is the maximum output (BTU/H) for a particular boiler Y,and

(5) R_(PG2) is the amplified-biased ramp-down variable for a particularboiler Y.

Preferably, the output percentage factor OPF for deadband DB is 5 forthe biased ramp-down of digital control voltage signal AN_(Y).

To modulate the rate-of-change of the unbiased or biased ramp-down ofdigital control voltage signal AN_(Y), the following equation [28] canbe utilized to control a timer gate that counts up to allow acalculation of digital control voltage signal AN_(Y) and is thereafterreset to begin a new count up sequence for the next calculation ofdigital control voltage signal AN_(Y):

IF E _(Y)<+DB and E _(Y)>−DB, THEN TGPV_(Y)=PA*TGF   [28]

where (1) TPGV_(Y) is a timer gate preset value,

(2) PA is a process acceleration scale value, and

(3) TGF is a time gate factor inversely correlated to a chosen outputpercentage factor OPF for deadband DB.

The inverse correlation of the timer gate factor TGF and the outputpercentage factor OPF is a function of the timing specification of thetimer gate and one or more designed output percentage factors OPF fordeadband DB. For example, the following table illustrates an inversecorrelation designed output percentage factors to a timer gate factorTGF in terms of the number times per second the timer gate should allowfor a calculation of the digital control voltage signal AN_(Y):

OUTPUT PERCENTAGE FACTOR OPF TIMER GATE FACTOR TGF 1 8 (10 times/8seconds) 2 7 (10 times/7 seconds) 5 6 (10 times/6 seconds) 10 5 (10times/5 seconds) 20 4 (10 times/4 seconds) 30 3 (10 times/3 seconds) 402 (10 times/2 seconds) 50 1 (10 times/1 seconds)

A benefit of equation [28] is as the calculated error E_(Y) of stage 306decreases, the rate of change of the modulation of the digital controlvoltage signal AN_(Y) is decelerated in view of a corresponding increasein the timer gate preset value TPGV_(Y). Conversely, as the calculatederror E_(Y) of stage 306 increases, the rate of change of the modulationof the digital control voltage signal AN_(Y) is accelerated in view of acorresponding decrease in the timer gate preset value TPGV_(Y).

Please note flowchart 400 is designed to execute digital calculations ofthe modulation control variable and digital control voltage signal andthus the requirement for equations [16] and [17]. Those having ordinaryskill in the art will appreciate that, in order to drive an analogcircuit of a boiler, the digital control voltage signal has to beconverted back into the analog control voltage signal.

Referring to FIGS. 8 and 9, those having ordinary skill in the art willappreciate the benefits of the process modulation algorithm and variousmodulation schemes of the present disclosure. Those having ordinaryskill in the art of the present disclosure will further appreciate howto apply equations [1]-[28] to various systems, in particular how todesign the various variables of equations [1]-[28] in view of theparticular type of devices to be controlled in accordance with thepresent disclosure. For example, FIG. 10 illustrates a system controller500 for implementing flowcharts 300 (FIG. 8) and 400 (FIG. 9) via awireline or wireless network with a number X of devices 600 of any type(e.g., boilers, chillers, pumps, dampers, etc.). By further example,FIG. 11 illustrates a system administrator 501 for executing stages S302and S304 of flowchart 300 (FIG. 8) via a wireline or wireless network todevice controllers 502 for executing stages S306 and S308 of flowchart300 as well as flowchart 400 (FIG. 9) on behalf of devices 600 (e.g.,boilers, chillers, pumps, dampers, etc.). Alternatively, administrator501 can partially or entirely execute stage S306.

FIG. 12 illustrates a condensing plant 710 employing one or morecondensing boilers, a non-condensing plant 711 employing one or morenon-condensing boilers and a hot water loop 712 employing a pipingsystem coupled to inlets and outlets of condensing plant 710 andnon-condensing plant 711. Water flow through hot water loop 712 isdesigned to pass by or through condensing plant 710 prior tonon-condensing plant 711 as shown in FIG. 12. Also shown are acondensing water flow meter WF1, a condensing return temperature sensorRT1, a non-condensing water flow meter WF2, a non-condensing returntemperature sensor RT2, and a system supply temperature system ST1.

In practice for multiple condensing boiler embodiments, condensing plant710 may have the condensing boilers in any serial, parallel orcombination arrangement relative to hot water loop 712. Similarly, inpractice for multiple non-condensing boiler embodiments, non-condensingplant 711 may have the non-condensing boilers in any serial, parallel orcombination arrangement relative to hot water loop 712.

Referring to FIG. 13, flowchart 720 is representative of a hybrid energyload calculation of the present disclosure.

Specifically, a stage S721 of flowchart 720 encompasses an energy loadcalculation that is dependent upon one or more operational conditions(e.g., temperature, pressure, power consumption, motion, etc.) ofcondensing plant 710. Generally, the following equation [29] serves as abasis for purposes of calculating an energy load for condensing plant710:

L _(C) =f(T _(RT1) , T _(RT2), GPM_(WF1))   [29]

where L_(C) is a calculated energy load (BTU/H) for condensing plant710,

T_(RT1) is the return temperature (° F.) sensed by condensing returntemperature sensor RT1,

T_(RT2) is the return temperature (° F.) sensed by non-condensing returntemperature sensor RT2, and

GPM_(WF1) is the number of gallons per minute flowing through hot waterloop 7712 past water flow meter WF1.

In one embodiment of stage S721 dependent upon a set-point temperatureof condensing plant 710, the following equation [30] may be utilized forpurposes of calculating an energy load for condensing plant 710:

L _(C)=((T _(SPC) −T _(RT1))+(T _(SPC) −T_(RT2)))*(GPM_(WF1)*WLG*MPH_(C))   [30]

where T_(SPC) is the condensing set-point temperature (° F.) ofcondensing plant 710,

WLG is the pounds of water per gallon within hot water loop 712, and

MPH_(C) is the minutes per hour condensing plant 710 is expected to beoperational for an hour time period.

In one embodiment of stage S721 for condensing set-point temperatureT_(SPC), a condensing reset temperature slope is derived from a graph ofa water temperature range and output air temperature range forcondensing plant 710. For this slope, one endpoint is plotted as themaximum water temperature/minimum outdoor air temperature and the otherendpoint is plotted as the minimum water temperature/maximum outdoor airtemperature, whereby condensing set-point temperature T_(SPC) is thewater temperature on the slope corresponding to a sensed outdoor airtemperature.

Upon completion of stage S721 of flowchart 720, device loadassignment(s), device output error calculation(s) and device outputmodulation control may be implemented for condensing plant 710.

Still referring to FIG. 13, stage S722 of flowchart 720 encompasses anenergy load calculation that is dependent upon one or more operationalconditions (e.g., temperature, pressure, power consumption, motion,etc.) of non-condensing plant 711. Generally, the following equation[31] or equation [32] may serve as a basis for purposes of calculatingan energy load for non-condensing plant 711:

L _(NC1) =f(T _(RT2) , T _(ST1), GPM_(WF1))   [31]

L _(NC2) =f(T _(RT2) , T _(ST1), GPM_(WF2))   [32]

where L_(NC) is a calculated load (BTU/H) for non-condensing plant 711,

T_(RT2) is the return temperature (° F.) sensed by non-condensing returntemperature sensor RT2,

R_(ST1) is the supply temperature (° F.) sensed by system supplytemperature sensor ST1,

GPM_(WF1) is the number of gallons per minute flowing through hot waterloop 712 past water flow meter WF1, and

GPM_(WF2) is the number of gallons per minute flowing through hot waterloop 712 past water flow meter WF2.

In one embodiment of stage S722 dependent upon a set-point temperatureof non-condensing plant 711, the following equation [33] or equation[34] may be utilized for purposes of calculating an energy load fornon-condensing plant 711:

L _(NC1)=((T _(SPN) −T _(RT2))+(T _(SPN) −T_(ST1)))*(GPM_(WF1)*WLG*MPH_(NC))   [33]

L _(NC2)=((T _(SPN) −T _(RT2))+(T _(SPN) −T_(ST1)))*(GPM_(WF2)*WLG*MPH_(NC))   [34]

wherein T_(SPN) is the set-point temperature (° F.) of non-condensingplant 711,

WLG is the pounds of water per gallon within hot water loop 712, and

MPH_(NC) is the minutes per hour non-condensing plant 711 is expected tobe operational for an hour time period.

Alternatively, equations [33] and [34] may be modified as follows toaddress a return temperature less than a condensing temperature limitCLT:

L _(NC1)=((T _(SPN) −T _(RT2))+(T _(SPN) −T _(ST1))+(CLT−T_(RT2)))*(GPM_(WF1)*WLG*MPH_(NC))   [35]

L _(NC2)=((T _(SPN) −T _(RT2))+(T _(SPN) −T _(ST1))+(CLT−T_(RT2)))*(GPM_(WF2)*WLG*MPH_(NC))   [36]

In one embodiment of stage S722 for set-point temperature T_(SPN), anon-condensing reset temperature slope is derived from a graph of awater temperature range and output air temperature range fornon-condensing plant 711. For this slope, one endpoint is plotted as themaximum water temperature/minimum outdoor air temperature and the otherendpoint is plotted as the minimum water temperature/maximum outdoor airtemperature whereby set-point temperature T_(SPN) is the watertemperature on the slope corresponding to a sensed outdoor airtemperature.

Upon completion of stage S722 of flowchart 720, device loadassignment(s), device output error calculation(s), and device outputmodulation control may be implemented for non-condensing plant 711.

FIGS. 14A and 14B illustrate an energy exchange system employing aboiler plant 730 including one or more boilers of any type, a chillerplant 731 including one or more chillers of any type, a primary hotwater loop W1 employing a piping system coupled to inlets and outlets ofboiler plant 730, a primary chilled water loop W2 employing a pipingsystem coupled to inlets and outlets of chiller plant 731 and an energyexchanger 732 for transferring thermal energy between primary hot waterloop W1 and primary chilled water loop W2.

In operation for a heating mode 740 as shown in FIG. 15A, boiler(s) ofboiler plant 730 are operational with pumps of boiler plant 730 (notshown) facilitating a flow of heated water through primary hot waterloop W1. Concurrently, chiller(s) of chiller plant 731 are inoperativeand valved off from primary chilled water loop W2 while pumps (notshown) of chiller plant 731 (not shown) facilitate a flow of waterthrough primary chilled water loop W2. In this scheme, energy exchanger732 transfers thermal energy from primary hot water loop W1 to primarychilled water loop W2, which now serves as a secondary hot water loopW2.

An energy load calculation for heating mode 740 is dependent upon one ormore operational conditions (e.g., temperature, pressure, powerconsumption, motion, etc.) of boiler plant 730 and chiller plant 731.Generally, the following equation [35] or equation [36] may serve as abasis for purposes of calculating an energy load for boiler plant 730:

L _(BP1) =f(T _(RT3) , T _(ST3), GPM_(WF3))   [35]

L _(BP2) =f(T _(RT3) , T _(ST3), GPM_(WF3) , T _(RT4) , T _(ST4),GPM_(WF4))   [36]

where L_(BP) is a calculated energy load (BTU/H) for boiler plant 730,

T_(RT3) is the return temperature (° F.) sensed by return temperaturesensor RT3,

T_(ST3) is the return temperature (° F.) sensed by system supplytemperature sensor ST3,

GPM_(WF3) is the number of gallons per minute flowing through primaryhot water loop W1 past water flow meter WF3,

T_(RT4) is the return temperature (° F.) sensed by return temperaturesensor RT4,

T_(ST4) is the return temperature (° F.) sensed by system supplytemperature sensor ST4, and

GPM_(WF4) is the number of gallons per minute flowing through secondaryhot water loop W2 past water flow meter WF4.

In one embodiment of heating mode 740 dependent upon a set-pointtemperature of boiler plant 730, the following equations [37] and/or[38] may be utilized for purposes of calculating an energy load forboiler plant 730:

L _(BP1)=((T _(SPB) −T _(RT3))+(T _(SP3) −T_(ST3)))*(GPM_(WF3)*WLG_(BP)*MPH_(BP))   [37]

L _(BP2)=((T _(SPB) −T _(RT4))+(T _(SP4) −T_(ST4)))*(GPM_(WF4)*WLG_(CP)*MPH_(CP))   [38]

wherein T_(SPB) is the set-point temperature (° F.) of boiler plant 730,

WLG_(BP) is the pounds of water per gallon within boiler plant 730,

WLG_(CP) is the pounds of water per gallon within chiller plant 731,

MPH_(BP) is the minutes per hour boiler plant 730 is expected to beoperational for an hour time period, and

MPH_(CP) is the minutes per hour the pumps of chiller plant 731 isexpected to be operational for an hour time period.

In practice, equation [37] will always be utilized for purposes ofcalculating the energy load for boiler plant 730, while equation [38]may or may not be utilized for purposes of calculating the energy loadfor boiler plant 730. For example, equation [37] may be utilizedexclusively, equations [37] and [38] may be added equally or weighted infavor of equation [37], or equations [37] and [38] may be averagedequally or weighted in favor of equation [37].

In one embodiment using set-point temperature T_(SPB), a resettemperature slope is derived from a graph of a water temperature rangeand output air temperature range for boiler plant 730. For this slope,one endpoint is plotted as the maximum water temperature/minimum outdoorair temperature and the other endpoint is plotted as the minimum watertemperature/maximum outdoor air temperature whereby condensing set-pointtemperature T_(SPB) is the water temperature on the slope correspondingto a sensed outdoor air temperature.

In operation for a chilling mode 741 as shown in FIG. 15B, chillers ofchiller plant 731 are operational with pumps of chiller plant 731 (notshown) facilitating a flow of chilled water through primary chilledwater loop W2. Concurrently, boiler(s) of boiler plant 730 areinoperative and valved off from primary hot water loop W1, while pumpsof boiler plant 730 (not shown) facilitate a flow of water throughprimary hot water loop W1. In this scheme, energy exchanger 732 transferthermal energy to primary chilled water loop W2 from primary hot waterloop W1, which now serves as a secondary chilled water loop W1.

An energy load calculation for chilling mode 741 is dependent upon oneor more operational conditions (e.g., temperature, pressure, powerconsumption, motion, etc.) of boiler plant 730 and chiller plant 731.Generally, the following equation [39] or equation [40] may serve as abasis for purposes of calculating an energy load for chiller plant 731:

L _(CP1) =f(T _(RT5) , T _(ST5), GPM_(WF5))   [39]

L _(CP2) =f(T _(RT5) , T _(ST5), GPM_(WF5) , T _(RT6) , T _(ST6),GPM_(WF6))   [40]

where L_(CP) is a calculated energy load (BTU/H) for chiller plant 731,

T_(RT5) is the return temperature (° F.) sensed by return temperaturesensor RT5,

T_(ST5) is the return temperature (° F.) sensed by system supplytemperature sensor ST5,

GPM_(WF5) is the number of gallons per minute flowing through primarychilled water loop W2 past water flow meter WF5,

T_(RT6) is the return temperature (° F.) sensed by return temperaturesensor RT6,

T_(ST6) is the return temperature (° F.) sensed by system supplytemperature sensor ST6, and

GPM_(WF6) is the number of gallons per minute flowing through secondarychilled water loop W1 past water flow meter WF6.

In one embodiment of chilling mode 741 dependent upon a set-pointtemperature of chiller plant 731, the following equations [41] and/or[42] may be utilized for purposes of calculating an energy load forchiller plant 731:

L _(CP1)=((T _(SPC) −T _(RT5))+(T _(SP3) −T_(ST5)))*(GPM_(WF5)*WLG_(CP)*MPH_(CP))   [41]

L _(CP2)=((T _(SPC) −T _(RT6))+(T _(SP4) −T_(ST6)))*(GPM_(WF6)*WLG_(BP)*MPH_(BP))   [42]

wherein T_(SPC) is the set-point temperature (° F.) of chiller plant731,

WLG_(CP) is the pounds of water per gallon within chiller plant 731,

WLG_(BP) is the pounds of water per gallon within boiler plant 730

MPH_(CP) is the minutes per hour chiller plant 731 is expected to beoperational for an hour time period, and

MPH_(BP) is the minutes per hour the pumps of boiler plant 730 isexpected to be operational for an hour time period.

In practice, equation [41] will always be utilized for purposes ofcalculating the energy load for chiller plant 731 while equation [42]may or may not be utilized for purposes of calculating the energy loadfor chiller plant 731. For example, equation [41] may be utilizedexclusively, equations [41] and [42] may be added equally or weighted infavor of equation [41], or equations [41] and [42] may be averagedequally or weighted in favor of equation [41].

In one embodiment of set-point temperature T_(SPC), a reset temperatureslope is derived from a graph of a water temperature range and outputair temperature range for chiller plant 731. For this slope, oneendpoint is plotted as the maximum water temperature/minimum outdoor airtemperature and the other endpoint is plotted as the minimum watertemperature/maximum outdoor air temperature whereby condensing set-pointtemperature T_(SPC) is the water temperature on the slope correspondingto a sensed outdoor air temperature.

FIG. 16 illustrates a boiler 750 having an inlet and an outlet connectedto a piping system. Also shown are a gas meter GM1, an inlet temperaturesensor IT, an outlet temperature sensor OT, and a water flow meter WF7.A real-time gas efficiency GF of boiler 750 is calculated in accordancewith the following equation [43].

GF ₅₀=(GPM_(WF7)*(T _(OT) −T _(IT)))/GAS_(GM1)   [43]

where GF₅₀ is a calculated gas efficiency for boiler 750,

T_(IT) is the inlet temperature (° F.) sensed by inlet temperaturesensor IT,

T_(OT) is the outlet temperature (° F.) sensed by outlet temperaturesensor OT,

GPM_(WF7) is the number of gallons per minute flowing through boiler 750past water flow meter WF7, and

GAS_(GM1) is the amount of gas flowing into boiler 750 past gas meterGM1.

This will enable a tracking of long term performance of boiler 750 overthe course of a time period T₀ to T₁.

FIG. 17 illustrates a series boiler arrangement of boilers 760-763having inlets and outlets connected to a piping system. Also shown, area gas meter GM2, a return temperature sensor RT8, an supply temperaturesensor ST8 and a water flow meter WF8. A real-time gas efficiency GF ofboilers 760-763 is calculated in accordance with the following equation[48].

GF ₇₆₀₋₇₆₃=(GPM_(WF8)*(T _(ST8) −T _(RT8)))/GAS_(GM2)   [48]

where GF₇₆₀₋₇₆₃ is a calculated gas efficiency collectively of boilers760-763,

T_(RT8) is the return temperature (° F.) sensed by return temperaturesensor RT8,

T_(ST8) is the return temperature (° F.) sensed by system supplytemperature sensor ST8,

GPM_(WF8) is the number of gallons per minute flowing through boilers760-763 past water flow meter WF8, and

GAS_(GM1) is the amount of gas flowing into boiler 750 past gas meterGM2.

This will enable a tracking of long term performance of boiler 750 overthe course of a time period.

In practice, more or fewer boilers may be employed, and any serial,parallel or combination of boilers may be employed.

FIG. 18 illustrates a boiler plant 770 employing one or more boilers ofany type(s), a hot water loop 771 and a pumping system 772 of one ormore pumps of any type(s). Also shown is a water flow meter WF9, areturn temperature sensor RT9 and a supply temperature sensor ST9. Inpractice for multiple-boiler embodiments, boiler plant 770 may have theboilers in any serial, parallel, or combination arrangement relative tohot water loop 771. Similarly, for multiple-pump embodiments, pumpingsystem 772 may have the pumps in any serial, parallel, or combinationarrangement relative to hot water loop 771.

FIG. 19 illustrates a flowchart 780 representative of a ΔT pumpingmethod of the present disclosure. Specifically, a stage S781 offlowchart 780 encompasses a determination as to whether pumping system772 is operating between minimum pressure limit P_(MIN) and maximumpressure limit P_(MAX). If pumping system 772 is operating betweenminimum pressure limit P_(MIN) and maximum pressure limit P_(MAX), thena stage S782 of flowchart chart 80 encompasses a modulation of pumpingsystem 772 in conformance with a ΔT setpoint for pumping system 772,whereby the ΔT setpoint represents a differential between supplytemperature T_(ST9) as sensed by supply temperature sensor ST9 and areturn temperature T_(RT9) as sensed by return temperature sensor RT9.

In one embodiment of ΔT setpoint, a reset temperature slope is derivedfrom a graph of a range of water temperature differentials and outputair temperature range for pumping system 772. For this slope, oneendpoint is plotted as the maximum water temperaturedifferential/minimum outdoor air temperature and the other endpoint isplotted as the minimum water temperature differential/maximum outdoorair temperature, whereby the ΔT setpoint is the water temperaturedifferential on the slope corresponding to a sensed outdoor airtemperature.

Referring back to stage S781, if pumping system 772 is not operatingbetween minimum pressure limit P_(MIN) and maximum pressure limitP_(MAX), then a stage S783 of flowchart 780 encompasses a reset ofpumping system 772 within minimum pressure limit P_(MIN) and maximumpressure limit P_(MAX).

A pumping system of a chiller plant may also be operated in accordancewith flowchart 780.

Two (2) additional features of the present disclosure include a datalogger factorization and a low fire/outdoor air modulation.

The data logger factorization is premised on a logging of the energyload and/or other operating points of a boiler plant and/or a chillerplant. Specifically, the data logger may be used as a limiting factor, afloor factor, a ceiling factor, or as any other known factoringvariable. For example, historical load on a data logger may be utilizedto increase or decrease an initial period of low-fire output forboilers. In this case, the period may be decreased for a historicallyhigher load experienced by the boilers for a particular use or time ofday. Alternatively, the period may be increased for a historically lowerload experienced by the boilers for a particular use or time of day.

The low fire/outdoor air modulation involves increasing or decreasing aninitial period of low-fire output for boilers in dependence on thetemperature of the outdoor air. For example, the initial period oflow-fire output is increased for an increase in outdoor air temperatureand decreased for a decrease in outdoor air temperature.

Again, those having ordinary skill in the art will appreciate thebenefits of the process modulation algorithm and various modulationschemes of the present disclosure. Those having ordinary skill in theart of the present disclosure will further appreciate how to apply theequations [29]-[48] to various systems, in particular how to design thevarious variables of the equations [29]-[48] in view of the particulartype of devices to be controlled in accordance with the presentdisclosure. For example, a system controller may implement theprocesses/schemes herein via a wired or wireless network with a number Xof devices of any type (e.g., boilers, chillers, pumps, dampers, etc.).By further example, a system administrator may execute various stages ofprocesses/schemes herein via a wired or wireless network to devicecontrollers for further stages of processes/schemes herein on behalf ofdevices (e.g., boilers, chillers, pumps, dampers, etc.).

While the disclosure has been illustrated and described in detail in thedrawings and foregoing description, the same is to be considered asillustrative and not restrictive in character, it being understood thatonly the preferred embodiments have been shown and described and thatall changes, modifications and equivalents that come within the spiritof the present disclosure provided herein are desired to be protected.The articles “a”, “an”, “said” and “the” are not limited to a singularelement, and may include one or more such elements.

1. A hydronic heating system, comprising: a water line for circulatingwater through a building; at least one boiler connected to the waterline for heating the water flowing through the water line; and a controloperably coupled to the at least one boiler, the control including atleast one processor configured for calculating a system energy load foroperating the at least one boiler, wherein a calculation of the systemenergy load is a function of a set-point water temperature for thehydronic heating system, a supply water temperature of water flowingrelative to a supply point of the water line, a return water temperatureof water flowing relative to return point of the water line and a flowrate of water flowing relative to a flow sense point of the water line.2. The hydronic heating system of claim 1, wherein the calculation ofthe system energy load includes a calculation of a set-point/supplydifferential between the set-point temperature and the supply watertemperature.
 3. The hydronic heating system of claim 1, wherein thecalculation of the system energy load includes a calculation of aset-point/return differential between the set-point temperature and thereturn water temperature.
 4. The hydronic heating system of claim 1,wherein the calculation of the system energy load includes a calculationof a set-point/supply differential between the set-point temperature andthe supply water temperature; a calculation of a set-point/returndifferential between the set-point temperature and the return watertemperature; and a calculation of a temperature summation of theset-point/supply differential and the set-point/return differential. 5.The hydronic heating system of claim 1, wherein the calculation of thesystem energy load includes a calculation of a condensing/returndifferential between a condensing temperature limit and the return watertemperature.
 6. The hydronic heating system of claim 1, wherein thecalculation of the system energy load includes a calculation of aset-point/supply differential between the set-point temperature and thesupply water temperature; a calculation of a set-point/returndifferential between the set-point temperature and the return watertemperature; a calculation of a condensing differential between acondensing temperature limit and the return water temperature; and acalculation of a temperature summation of the set-point/supplydifferential, the set-point/return differential, and thecondensing/return differential.
 7. The hydronic heating system of claim1, wherein the calculation of the system energy includes a calculationof a product of the flow rate of the water flowing relative to a flowsense point of the water line, and a weight of the heat water flowingthrough the water line.
 8. The hydronic heating system of claim 1,wherein the calculation of the system energy includes a calculation of aproduct of the flow rate of the water flowing relative to a flow sensepoint of the water line, a weight of the heated water circulatingthrough the water line, and a specified operational time period of thehydronic heating system.
 9. The hydronic heating system of claim 4,wherein the calculation of the system energy includes a calculation of aproduct of the temperature summation, the flow rate of the water flowingrelative to a flow sense point of the water line, and a weight of theheat water circulating through the water line.
 10. The hydronic heatingsystem of claim 4, wherein the calculation of the system energy includesa calculation of a product of the temperature summation, the flow rateof the water flowing relative to a flow sense point of the water line, aweight of the heated water circulating through the water line, and aspecified operational time period of the hydronic heating system. 11.The hydronic heating system of claim 6, wherein the calculation of thesystem energy includes a calculation of a product of the temperaturesummation, the flow rate of the water flowing relative to a flow sensepoint of the water line, and a weight of the heat water circulatingthrough the water line.
 12. The hydronic heating system of claim 6,wherein the calculation of the system energy includes a calculation of aproduct of the temperature summation, the flow rate of the water flowingrelative to a flow sense point of the water line, a weight of the heatedwater circulating through the water line, and a specified operationaltime period of the hydronic heating system.
 13. The hydronic heatingsystem of claim 1, wherein at the at least one boiler includes at leastone condensing boiler.
 14. The hydronic heating system of claim 1,wherein at the at least one boiler includes at least one non-condensingboiler.
 15. The hydronic heating system of claim 1, wherein the controlis configured for independently operating each boiler in a manner thatmatches the system energy load to operating characteristics of eachboiler enabled for heating water flowing through the water line.
 16. Thehydronic heating system of claim 15, wherein the match of the systemenergy load to operating characteristics of each enabled boiler includesa heat load assignment of each enabled boiler based on the operatingcharacteristic of each enabled boiler, each heat load assignment beingat least a portion of the system energy load.
 17. The hydronic heatingsystem of claim 16, wherein each enabled boiler is independentlymodulated as a function of a comparison of the heat load assignment ofthe enabled boiler to a heat output of the enabled boiler.
 18. Thehydronic heating system of claim 1, further comprising: for each boiler,a water pump for circulating water through the boiler, wherein thecontrol is configured to modulate each water pump to maintain a constanttemperature differential between an inlet temperature and an outlettemperature of water flowing through a corresponding boiler.
 19. Thehydronic heating system of claim 18, wherein the water pump is modulatedto vary the flow rate of water flowing through the boiler as required tomaintain the constant temperature differential between the inlettemperature and the outlet temperature of water flowing through thecorresponding boiler.
 20. The hydronic heating system of claim 1,wherein the water line is a closed water line.